In recent years, video cameras and electronic cameras using solid-state image sensors of CCD (Charge Coupled Device) type, CMOS (Complementary Metal Oxide Semiconductor) type, and the like are in wide use. In the solid-state image sensor, multiple pixels are arranged in a matrix. Each pixel of the solid-state image sensor has a photoelectric converter that converts light received by the pixel to an electric signal. Signal lines, etc., through which the electric signals of the photoelectric converters of the respective pixels are read, are arranged around the photoelectric converters. Light entering from a subject via a lens of a video camera or an electronic camera comprising a solid-state image sensor is imaged on the pixel array. The imaged light is converted to the electric signals by the photoelectric converters.
Not all the light imaged on the pixels necessarily enters the photoelectric converters. To improve light collection, microlenses are arranged in a matrix on the side where light enters the pixels. Light that otherwise would be useless is condensed in the photoelectric converters by the microlenses. See Japan Unexamined Patent Publication No. Sho 60-59752.
A conventional microlens is semispherical and its plan profile is circular, whereas the plan profile of a pixel is generally quadrangular. Thus, the respective profiles of the pixel and of the microlens do not match each other, resulting in incomplete convergence of light on the photoelectric converters. One approach to preventing this problem is discussed in Japan Unexamined Patent Publication No. Hei 5-326913, in which the plan profile of the microlens is made quadrangular or the plan profiles of the pixel and of the microlens are made polygonal.